Prior patents, such as U.S. Pat. No. 6,252,971 for “Digital watermarking using phase-shift stoclustic screens,” by S. Wang, hereby incorporated by reference in its entirety, describe a method to embed correlation-based phase-shift digital watermarks into halftone screens. By overlaying a transparency on the prints generated by the special halftone screen, for example as a public key, invisible watermarks can be retrieved. For color images, the watermark was embedded into all or a selected color channel in a dot-on-dot arrangement.
Disclosed in embodiments herein is a method for digital watermarking of an image, comprising: receiving the image to be watermarked; determining the watermark to be embedded in the image; embedding an invisible digital watermark into the image using a multi-dimensional threshold operation, wherein at least one input thereto is a phase shift value; and outputting the watermarked image containing the embedded invisible digital watermark.
Further disclosed in embodiments herein is a method for digital watermarking of an image, comprising: receiving the image to be watermarked; determining a watermark to be embedded in the image; embedding the watermark into the image using a multi-dimensional threshold array, wherein at least one input thereto is a phase shift value; and outputting the watermarked image containing the embedded digital watermark, wherein the image includes an invisible digital watermark.
Also disclosed herein is a system for digital watermarking of an image, comprising: an input image source; image memory for storing the input image to be watermarked; watermark memory for storing the watermarks to be embedded in the image; and an image processor for embedding a plurality of invisible digital watermarks into the image, said image processor including a multi-dimensional threshold array where at least one input thereto is a phase shift value, and wherein the watermark is embedded into the image
The various embodiments described herein are not intended to limit the invention to those embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the appended claims.